200 cid operating temperature

Nice to find these forums. I got a 1975 Maverick 4 door with the 200 inline six engine. I've been driving it for about a year now, bought it with only 13k miles, and we are closing on 21k. Love the car, but it was as bare bones as could be as a barn find. So the few things I have done was put in an aftermarket underdash AC unit, which required replacing the radiator and moving to an electric fan. Put in a stereo since it didn't have anything from the factory, and a few little things here and there. Most recently I did install a temperature gauge, since it didn't have one originally. I did this because I felt the car was way too damn cold in the winter, and in a few storms I needed a coat in the car to stay warm on the highway, and the defrost up front was just barely able to do the job. My first thought was to do a warmer thermostat, but I backed off since I didn't actually have a temperature gauge to know what it was actually running at so I figured it safer to do that first and see what I got going before I mess with anything. So today was my first time driving with the gauge, and I was curious what optimal temperatures for this car are. I didn't see the operating range in the manual, but only had time to glance, and I figured I'd just ask here see what people have to say. I also noticed that 205 thermostats are available for this car, but that seems kinda high to me based on others I have seen. I live in southern colorado, so the temps range from sub zeros to over 100, so looking for whats best all around.

 

These cars never had great heaters, but your heater core may need replaced.
They came from the factory with 195° thermostats, but one reason for that was emissions.
Today's cars run between 210° and 220°, but I don't like my old cars to run over 200° on a hot day. My Maverick with mild performance V-8 runs between 180° and 190° cruising down the road (170°-175° on a cool early morning in the summer) and typically not over 200° idling.
This is with a 2-row Champion radiator, stock fan & shroud, and 170° thermostat...

 

I should say I did replace the radiator with a 4 core bigger one because the tiny original wasn't going to be up to the task for AC. I'm guessing the operating temps for a certainly not performance 200 cid would probably still be around the same range. Thanks for the info.

 

All round huh? Likely a pipe dream, likely require seasonal swapping of thermostats. A 170* in summer and hottest you can find for winter. Probably still have to cover half of the radiator at temps below 35*F. If it still has orig heater core no doubt a new one should help.

With the HD radiator for year round, a 195* will be mandatory. Use a thermostat WITHOUT the burp opening, yes they are a PITA but allow engine to warm up much faster. Probably need to remove a heater hose when refilling system.

As long as you use a good oil, occasional temps of 220-230* will be fine.
A 5W-40 Motorcraft diesel oil will have extra zinc, and protects to over 250*F.

Size of engine makes a difference in heater performance. Eons ago I had a 289 '64 Galaxie with 180* stat. In Iowa winter, like to have froze to death. Found it was somewhat acceptable using a 195*. Next spring swapped engine to a 390 that had 180* stat. Figured come winter, I'd have to change to the 195*. Nope, the big lump made plenty of heat with the 180*.

 

...

 

I live where you do. Drove my Maverick year-round for 10 years and always used the same thermostat, which was a 180-degree. The heater worked better with a 195, but still worked "good enough" with the 180. I also drove a '75 Comet with a 250 for one winter. I can't remember if it had a 180 or a 195 (long time ago!), but I never changed it for different seasons.
Diesel oil is formulated for diesel engines. There is more ash content than the oil formulated for gasoline engines. People have gotten the idea that since it has 1,000 ppm (used to be 1200) of ZDDP, they should put it in their old gasoline engines. If were a "one size fits all" oil, it wouldn't say 'Diesel' on the container. Use a conventional motor oil for gasoline engines and if you're concerned about ZDDP, use an additive. Perhaps a 5w-30 in winter and a 10w-40 in summer...

 

Do you have PDS(product data sheet) showing the ash difference? Till last few years diesel oil had dual classification for gas and diesel engines. API dropped the gas requirement as that required additional certification. I've used the stuff for years and that was well prior to the zinc scare...

 

https://www.motortrend.com/how-to/diesel-oil-in-gasoline-engine/

 

If your setup has adjustable fan control, possibly fan is running more than necessary hampering your heat output!

 

Well I appreciate the inputs from everyone. I have the 200, and ideally wont be upgrading it for a long time. I got a 83 Trans am for fun stuff, the Maverick is here for what it was build for, a simple nice car, and hopefully a family car to drive every day. Now my new temp gauge allows me to set a warning alarm for when it's getting too hot, so what temp should I set that for where I need to be concerned? That way I'll have a warning for when its getting hot enough for me to worry about damage. I had an overheat issue and it was obviously boiling, but that happened when the voltage regulator died and the battery was drained nearly completely on the road. Luckily a good old O'Reilly happened to have one in stock and fixed it. I just was wondering where to set that warning temp at now.

 

interesting...thanks

 

Wow, I have a '83 Trans Am too...

 

I say MT is FOS

While Motorcraft isn't forthcoming with their specs(write for info) Mobil-1 has plenty of data. Their 5W-40 diesel oil meets SL(pre zinc reduction) and SM specs for gas engines. From '70s engine oils have progressed through at least 10 revisions, anything out there today far surpasses the dino juice we were buying back then. For most part phosphorus supplements zinc in all oils(yes gas), been proved by PDS & oil analyzations over & over.

https://www.mobil.com/en/lubricants...cts/products/mobil-1-turbo-diesel-truck-5w-40

https://www.mobil.com/en/lubricants...SHy48W-Wmpuv4Fu3kdxoCEt0QAvD_BwE&gclsrc=aw.ds

 

There are plenty of other sources besides Motor Trend that say the same thing.
Why not just use a motor oil that is formulated for your specific application? Why do so many people think they know more than the engineers who develop the stuff? AS IF it was a "happy accident" that diesel motor oil is 'better' for a gasoline engine than the oil that was formulated for it, and the engineers didn't know about it. If one oil was fit for all engines, there would be no reason to put "DIESEL" on the container...

 

My Maverick originally had a 200 and ran so cold in the winter that I would block half the radiator with a piece of tempered wall board to help the coolant retain heat. My grandmother's '73 with a 250 was the same way.